Mechanism of Hop-Derived Terpenes Oxidation in Beer

Terpenes are the main constituents of hops essentiol oil and contribute to the singular sensory properties of beer. However, terpenes are sensitive to oxidation leading to quality loss during beer aging. Herein, the reactivity of terpenes towards 1-hydroxyethyl radical has been determined employing a competitive kinetic approach using the spin-trap α-(4-pyridyl-1-oxide)- N-tert-butylnitrone (4-POBN). The apparent rate constant (kapp) for the reaction of terpenes with 1-hydroxyethyl radical ranges from (3.9 ± 0.2) × 105 to (1.5 ± 0.2) × 107 L mol−1 s−1 for β-pinene and terpinolene, re...